Chandler Evans Inc.

Colt Industries Inc.

Godwin L Noell

Jack G Sundberg

Frank A Leachman, Jr

Paul L Haynes, Jr

A variable displacement vaned fuel pump (10) is suitable for inclusion in a fixed displacement fuel control system for a gas turbine engine. The pump includes two track elements (34,36) having cam surfaces (42) which engage cam followers (44) on a cam actuation ring (40). A link (66) having a predetermined spring load maintains the track elements in their radially inner maximum displacement positions until the vane force and pressure forces drive the track elements radially outwardly, moving the actuation ring against its spring load. Displacement of the pump is reduced in the radially outward positions of the track elements which reduces the required bypass flow to hold a head constant across a fuel metering valve and attendant fuel heating.

Vane fuel pump having reduced displacement at high speeds

A pumping system has a main pumping unit (14) and a backup pumping unit (16) mounted in a common housing (4) and adapted to be driven by a drive member (44). The main pumping unit is connected to the drive member by a main drive coupling (68) which incorporates a reduced shear section (76) designed to fail upon a jamming or seizure of the main pumping unit. A backup drive coupling (78) connected to the backup pumping unit is adapted to be axially displaced and threadably connected to the drive member after stoppage of the main pumping unit. An actuation device (18) functions to axially displace the backup drive coupling to establish threaded engagement. When the backup drive coupling is engaged with the drive member, the backup pumping unit will provide flow.

Method and apparatus for main fuel pumping system having backup pump

A centrifugal main fuel pump (10') for a gas turbine engine has a housing (12') in which a centrifugal impeller (16') is mounted for rotation. The centrifugal impeller includes a disc (24') which carries starting flow impeller elements (34) which are positioned in a radially outer location on the disc and also carries main flow impeller elements (26') positioned in a radially inner location on the disc. The starting flow impeller elements discharge to a starting flow collector (38) and diffuser (44) and the main flow impeller elements discharge to a separate collector (30') and diffuser (32'). The starting flow impeller elements produce adequate fuel flow at the pressure necessary for engine lightoff while the main flow impeller elements are adapted to supply engine fuel flow demand in the normal range of operation. A check valve (46) prevents starting flow from returning to the centrifugal impeller. The check valve opens to allow the main flow impeller elements to supply fuel when their discharge pressure exceeds that of the starting flow impeller elements. The addition of a starting element to the impeller results in minimal additional parasitic power loss.

Centrifugal main fuel pump having starting element

A gear pump suitable for pumping contaminated fuel has a lubrication passage in a pump bearing which receives fuel from the clearance volume between the bearing and the housing in the pump discharge arc. The clearance entrance between the bearing and the housing, which functions as a filter, is smaller than the passage so that contaminants traversing the clearance will not obstruct the passage. Since only contaminants smaller than the clearance entrance can enter the passage, the passage may be made sufficiently small so as not to adversely affect pump performance.

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Winsted, CT, United States of America

Godwin L Noell